Hearing aid



FIG. 1 is a side view of a hearing aid of my design;

FIG. 2 is another side view of the hearing aid of my design;

FIG. 3 is a perspective view of the hearing aid of my design;

FIG. 4 is another perspective view of the hearing aid of my design;

FIG. 5 is another perspective view of the hearing aid of my design;

FIG. 6 is another perspective view of the hearing aid of my design; and,

FIG. 7 is another perspective view of the hearing aid of my design.

The ornamental design for a hearing aid, as shown and described.